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Shop Heat Questions

Greetings all

For the past seven years I have been answering this question rather than asking it, but the times they are a changin'...

Currently I have a radiant propane system which works very well and with which I am happy. However, last fall we installed an outdoor wood furnace with the capability to heat several buildings. We just heated the house last winter, but I am considering heating the shop as well. I need to make a decision soon, as we are planning on paving the driveway, and if I decide to heat with the outdoor furnace, I will need to trench across it. If it gets paved first, you can just believe I am not putting a ditch across it! What I mean specifically is, I need to decide if I am going to use this heat source at all ever. I can put the pipes in now (not a small expense) or forever hold my peace.

If I do go with heating the shop via the outdoor furnace, I have to make a choice in the type of heater that I am going to use. Probably the most economical and easiest to install would be a heat exchanger with a forced hot air system. I am not really enthusiastic about that for several reasons. Least economical (read financially unviable) is pulling all the tools out of the shop and installing a radiant heat system in the floor. I could also install some radiators in the wall somewhere, but I do not have a lot of wall space available. I am open to suggestions regarding one of these forms of heat.

I am posting to ask others what they have done that is pertinent to my sitation here. What I am looking for specifically is experience from people who have forced hot air in their shops or radiant heat via hot water in one of its numerous forms.

I don't know if I qualify other than having forced air HVAC in my shop. I have a Trane heat pump that keeps the shop at 74 in the summer and 68 in the winter. Yes, it isn't a Pennsylvania winter, but the summers can be nothing to sneeze at.

One consideration is how much insulation you are willing to throw at the project. How good are the windows and doors? Are you going to heat it day and night? If you go with a central heating system, 'the more insulation the better' is the mantra. IMO, the best thing to do is to price all the components that would go into a forced air heat system, and then look at the payback; you probably did that for your home heating system. It isn't clear to me, but you don't plan on running underground duct work from your home furnace to the shop do you?

Another option would be to dig the ditch and put in a pipe of the appropriate size under the new driveway and just leave it until you decide what you truly want to do.

With the cost of propane I'd at least lay the pipes. I have one of those hanging propane heaters and it is in effect a forced air system. Yea, it blows dust but if dust becomes a real problem for finishing a finishing room is certainly a cheap option. I think having an alternative to propane or at least a cheap supplement would be a wise decision.

You got a link to the outdoor furnace? My house goes through about 1400 gals of oil and if I could supplement that with something like the outdoor furnace it might well be worth it.

Edit: As far as insulation is concerned. I know your shop, like mine is a leaky barn. I tightened my shop up this winter and it made a very big difference but I only have one room in the barn and sealing is pretty huge task. If you can get it sealed then think about the insulation...if not insulation makes little difference.

Last edited by Bill Esposito; 04-29-2006 at 5:04 PM.

Bill Esposito
Click on my user name to see the link to My Personal WoodWorking and Tool Review Pages

What about laying some large conduit or possibly a small culvert down at the appropriate depth. Seal the ends of with some plugs of some sort (expansion foam inside a plastic bag comes to mind) and mark the ends really well. I would be thinking of a piece of romex from each endup to near the surface with a large piece of scrap metal attached to it so that you can find it with a metal detector. That way if you decide to go ahead with it at a later point in time you would just need to find the cables and run the trench up to them.

Bill,
Since you have invested in an outdoor wood furnace that has the capability of heating several buildings, it certainly makes sense to me to run piping to your workshop now, before you pave your driveway. If your current budget would be strained by running pipes all the way to the workshop, could you at least run beneath the drive and cap stubs there?

In-slab hydronic systems have slower response times for changing comfortable working temp than do either your current radiant propane heater or forced air hydronic units. A radiant slab also performs best when well insulated, at its perimeter and beneath. The system(s) you choose will be dependent on your shop time requirements and the insulation that you have and/or can add to you shop.

Long term considerations for you may be where you place your bet on future fossil fuel cost and availability. Gas burning (LPG and NG) furnaces are highly efficient transformers of energy, but based on my take of you thus far, so are you. In your search for wild grained burls, you will likely have enuf cords of straight grained splittable wood to feed the hearth fires of your home.

A wall mounted forced-air hydronic heater can transfer a lot of heat fast. What I really suggest you do Bill, is talk to an HVAC guy or so; look them in the eye, and I’m confident that you will be able to hear whether there is substance to their words.

I second or third.....or whatever putting in a piece of conduit and plugging the ends up, before the paving, and then you can run anything you want at a later date. You could probably find an old piece of 6" junk pipe to use for that, OR, a few feet of "heavy wall" 6" S&D PVC pipe with end caps just stuck on with no cement would be ideal if buried 18" - 24" deep.

"Some Mistakes provide Too many Learning Opportunities to Make only Once".

At the least I would put pipe under the driveway and cap it. I would consider putting in a couple pipes or conduits for down the road since you never know what you might want to do latter. You can then make the decision about heat down the road even years from now.

When I built my house I pulled spare wires from the fuse panel to the attic and the crawl space just in case. I have used two in a year of being in the house. I am a big fan of adding extras/planning ahead. I pulled tons of extra Cat5 and video coax even though I don't have a need right now.

Never had forced air in a shop (always had it the house) but I would think keeping a filter cleaned would a constant job.

Bill,
I have radiant heat(hot water) that was installed when I built the shop. It has a crawl space underneath so it under the floor(as opposed to in a slab. I agree with you that taking everything out of your shop would be a nightmare. However, I do think that the radiant floor heat is one of the best decisions that I made when building it. You don't know it's there other than the shop is not cold. No moving air, filters, exhaust, etc. It keeps my shop extremely comfortable all winter.
I agree with Jeff, put the pipe under the road and cap it and keep your options open.

Bill, I also have an outdoor wood stove and I found an old hot water radiator which I installed in a corner of the shop. I have a thermostat to control the radiater through a zone valve and when it is real cold outside I blow a fan through the radiator. I can keep the shop at 65 during the coldest winter days. The fan is going by the wayside when I install a large dust filter/blower directly over the radiator this summer. I would bury a section of pvc pipe, 6" dia. or so and cap the ends, for future pex lines. Insulation is by far the most important investment for keeping the shop heated. I plan on adding a lot more insulation to the ceiling/attic of the pole barn this summer. My shop is 18x32 with a 12' ceiling. I suppose you could put radiant tubes in the ceiling, if the ceiling was well insulated, and direct an air flow across the ceiling to circulate the warm air. Or maybe build a plenum hung from the ceiling and blow the air from a dust filter through it if floor space was at a premium. Just a thought, I have no idea if it would work well. I don't see how it would be any different from a ceiling mounted heater.

I second, third, or fourth the idea of burying a conduit of some sort. I'd go with 4" ABS sewer & drain or even 6". Not terribly expensive and if you ever needed it, it's there for you. I wished I had done the same thing with I added a driveway to my house. I wanted to run a water line a year or so later and figured it wasn't worth it so I don't have a water line where I'd like it now.

Bill,
Since you have invested in an outdoor wood furnace that has the capability of heating several buildings, it certainly makes sense to me to run piping to your workshop now, before you pave your driveway.

This summarizes my thoughts as well. You already have bitten off a substantial chunk of the financial burnden...and as long as I'm spending your money "lets" put in the in floor radiant too.
Chad

Better to keep silent and be thought a fool, then to open your mouth and remove all doubt.

Thanks for the replies everyone. Burying the pipe is pretty much a given, since it will be a lot cheaper than doing so after the fact. I am going to give the folks who installed the furnace for me a call and see what they have to say as well. I appreciate all the insights.

You got a link to the outdoor furnace? My house goes through about 1400 gals of oil and if I could supplement that with something like the outdoor furnace it might well be worth it.

Hi Bill

I got my outdoor furnace from Heatmor, www.heatmor.com. You can also try http://www.outbackheatinginc.com/ for their east coast distributor. We looked at several, but the details of this one made the choice pretty simple. It can burn coal, the ashes come out in a separate pan, and it has a forced draft. We burned 1300 gallons of oil the previous winter. After installing this thing (and we are heating an old drafty stone house) we burned about 125 gallons while learning to adjust it, another 60 gallons or so the week I had bronchitis, and after that, nothing until we shut it off for the season. If you want some more details, let me know.